302 CASA GRANDE EUIN. [eth.ann. 13 



each four or five times the size of the Casa Grande rnin, resting on a 

 flat topped pedestal or terrace about 5 feet above the general level. The 

 summits of these mounds, which are nearly flat, are some 13 feet above 

 this level. The sides of the motinds slope very sharply, and have suf- 

 fered somewhat from erosion, being cut by deep gullies, as shown in 

 figure 328, which is an enlargement from the map. It has been stated 

 that these structures were mounds, pure and simple, used for sacrifice 

 or worship, resembling somewhat the Avell-known pjTamid of Cholula; 

 but there is no doubt that they are the remains of house-structures, 

 for a careful examination of the surface on the slopes, reveals the ends 

 of regular walls. The height is not exceptional, the mound on the 

 east being less than 3 feet lower, while the one on the southeast lacks 

 less than 4 feet of its height. The characteristic feature, however, 

 and one difflcult to explain, except on the hypothesis stated, is the 

 sharp slo]ie of the sides. It will be noticed that the raised base or ter 

 race on which the mounds are located is not perfectly flat, but on the 

 contrary has a raised rim. This rim seems quite inconsistent with the 

 theory which has been advanced that the terrace was built uj) solidly 

 as a terrace or base, as in that case it would seem natural that the slope 

 from the base of the mounds to the edge of the terrace would be con- 

 tinuous. 



There is an abundance of room between the crest of the rim and the 

 base of the terrace for a row of single rooms, inclosing a court within 

 which the main structirres stood, or such a court may have been cov- 

 ered, wholly or partly with clusters of rooms, single storied outside, but 

 rising in the center, in two main clusters, three or more stories high. Such 

 an agglomeration of rooms might under certain conditions produce the 

 result seen here, although a circumscribing heavy wall, occupying the 

 position of the crest of the rim and inclosing two main clusters each 

 rising three or more stories, might also produce this result. The difli- 

 culty with the latter hypothesis is, however, that under it we should 

 expect to find a greater depression between the base of the mounds 

 and the edge of the terrace. The most reasonable hypothesis, there 

 fore, is that the space between the base of the mounds and the edge 

 of the terrace was occupied by rooms of one story. This would also 

 help to explain the steepness of the slopes of the mounds themselves. 

 The walls of the structures they represent, being protected by the 

 adjacent low walls of the one-story rooms, would not suffer appreciably 

 by undermining at the ground level, and if the central room or rooms 

 of each cluster were higher than the sui-rounding rooms, as is the case 

 in the Casa Grande ruin, the exterior walls, being usually heavier than 

 the inner walls, would be the last to succumb, the clusters would be 

 filled up by the disintegration of the inner walls, and not until the 

 spaces between the low one-story walls surrounding the central cluster 

 were nearly filled up would the pronounced disintegration of the outer 

 walls of the structures commence. At that period the walls were prob- 



